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CMSD6310 Audition l > Psychoacoustics ll > Flashcards

Psychoacoustics ll Flashcards

1
Q

What is loudness?

A

The perception of sound strength, and related to the sound level. It is subjective and can only be measured behaviorally

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2
Q

What other factors affect loudness? (3)

A

Frequency, duration, other signals’ presence

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3
Q

Based on the arbitrary scale, what were the general criteria for loudness regarding how many dB results in what multiplied change in loudness?

A

A 10db level change results in 2 times loudness.

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4
Q

In the SL measurement, what does that SL stand for? What is the 0dB in this case?

A

Sensation level where the individuals threshold is 0dB and the variation from that is for the loudness

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5
Q

For the original loudness scale, what frequency was used and at what intensity to get the arbitrary units?

A

800 Hz tone at 100dB

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6
Q

What was used in the frequency and intensity used in the sone scale to define the arbitrary one sone?

A

1000hz with a 40 dB tone.

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7
Q

As per the sone scale, what is the doubling or halving?

A

2 or 0.5 sones.

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8
Q

What is the general equation to convert the sone loudness to intensity (where it is a physical unit, not dB):

A

L=KI to the power of e where L is loudness, K is a constant (not important here), I is intensity and e is exponent

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9
Q

When there is a 10dB change in the intensity, how many times does the Sone change by?

A

2

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10
Q

At which level does the general idea that a 10dB change in intensity results in a 2-time change in loudness not apply?

A

At the low levels.

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11
Q

For the equal loudness contour, what scale is used?

A

Phon scale; How we perceive it as loud doesn’t depend on the actual SPL.

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12
Q

What does the phon scale use as its reference?

A

It uses 1000Hz, and at this frequency, the Phon is equal to the SP.

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13
Q

How are the other phons obtained?

A

The SPL s based on the equal loudness of that 1k reference curve. For 200hz, has to be 12 dB before can hear it (find it on the y-axis);

https://www.youtube.com/watch?v=Zouo4hakl2g excellent video

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14
Q

Overall, what is the difference in the continuous shape for the low SPL and the high SPL in the Phon scale?

A

At the low SPL, requiring the same Phon is largely varied with frequency. At the high, the variation across frequencies is less.

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15
Q

These questions are based on the impact of the contour shape on the dynamic range and loudness growth: what does the dynamic range measure?

A

The SPL difference between the floor and the ceiling.

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16
Q

These questions are based on the impact of the contour shape on the dynamic range and loudness growth: What is changed and what remains the same in the dynamic range?

A

The ceiling is not changed (the upper limit) but the floor varies

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17
Q

These questions are based on the impact of the contour shape on the dynamic range and loudness growth: What is the most sensitive region? What does the dynamic range look like in this sensitive region (small or large)?

A

1000 to 4000Hz LARGE DYNAMIC RANGE!

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18
Q

These questions are based on the impact of the contour shape on the dynamic range and loudness growth: What is the characteristic of the low frequency on these curves?

A

There is a smaller dynamic range and faster loudness growth.

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19
Q

What are the two characteristics that the loudness contour shows the impact of the sense of sound?

A

The boomy and tinny sounds

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20
Q

Describe Boomy and Tiny characteristics.

A

Boomy refers to that low-pitch, resonant sound that is apparent when amplified. Tinny refers to the higher pitch that becomes audible at a lower level.

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21
Q

What is a sound level meter?

A

Hand-held acoustic measuring instrument for acoustic measurements commonly used in noisy or industrial environments

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22
Q

Which filter network is used for a quiet environment?

A

Filter network A.

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23
Q

Where is there more weighting for the filter being used in a quiet environment?

A

These are the filters used in a sound level meter to make the instrument more nearly approximate the average human ear. The different contours were intended to match the ear at different sound intensities, so they are relative sound pressure levels.

24
Q

Which filter network is used for an environment with a high level of noise?

A

Filter C
In C, it is essentially a flat response like our ear at high sound levels

25
Q

What is a critical band?

A

The band in which the sound is “heard” by a Hair Cell and connected SGNs. It is the bandwidth of sound being heard by neurons in a channel.

26
Q

What change occurs across frequency and in relation to which acoustic parameter?

A

The intensity just because of the impact of bandwidth on intensity. Within the critical band, the loudness won’t change.

27
Q

What happens to the acoustic parameter above when increasing the bandwidth of the signal beyond that critical band? Why?

A

loudness will increase since the signal level is well above the threshold; when it spreads to more than one CB

28
Q

What happens when increasing within this critical band?

A

Redundant loudness won’t change within the CB

29
Q

How can loudness be maintained as the bandwidth changes?

A

If the bandwidth increases, decrease the intensity so that the ‘loudness’ can be maintained.

30
Q

What is adaptation?

A

The sensitivity decreases during the signal presentation, and the response to the non-novel signal has a reduced response.

31
Q

When is sensitivity back?

A

When there is a new signal.

32
Q

How is fatigue different than adaptation?

A

Fatigue= decreased of sensation to all stimuli after the signal presentation,
Adaptation = Sensation is regained for new stimuli

33
Q

How is adaptation measured?

A

Loudness matching in which when ear hears a continuous sound, and the loudness is matched by presenting a pulsed signal to the other ear and seeing the change over time.

34
Q

What kind of signal is not adapted?

A

Pulsed signal.

35
Q

What were the three main results of the loudness-matching experiment?

A

Specific to the binaural presentation,
Large variation across individuals,
More significant at only low SL, More at higher frequency (not shown).

36
Q

Adaptation is level dependent, meaning larger adaptation at ___________________________ and a ___________________________________________________

A

larger adaptation at lower sound levels and a large variation across individuals.

37
Q

What is masking?

A

When one sound interferes with the sensation of another sound.

38
Q

What is loudness recruitment?

A

Refer to the abnormal rapid growth of loudness with stimulus level; the term is reserved to SNHL.

39
Q

How is the loudness growth similar to the masking results? What is the difference?

A

The behavior of the loudness growth in those with sensorineural hearing loss is similar to the masking of normal hearing.

40
Q

What are 3 reasons that masking is important?

A

It occurs in our hearing environment and has a great impact on our hearing; It is a useful tool to study hearing; It has important clinical applications

41
Q

What does it mean that “masking changes the threshold”?

A

A masked threshold is usually higher than the threshold in quiet.

42
Q

How does masking occur as it relates to the basilar membrane?

A

The vibration produced by the masker occupies all auditory channels underneath and all the neurons are excited. Therefore it is an excitation pattern mechanism.

43
Q

What are the three maskings “types” / variations discussed briefly in class?

A

Energetic, informational, partial

44
Q

What is the masking tuning curve?

A

Masking TC is how the masked threshold by a tone masker changes with signal frequency.

45
Q

What is the psychophysical tuning curve and how does it show frequency selectivity?

A

The Psychophysical TCs is a masking TC obtained in the behavioral tests and shows the threshold of tone masking as the function of masker frequency. At each frequency, a measurement for the lowest threshold of masker that can interfere with the hearing of the targeted tone is measured. The change of masking with frequency shows in what frequency range this particular channel is sensitive. This frequency range for effective masking is what this channel can hear (or be selective to). The critical band is the concept that is represented by this selectivity.

46
Q

Why does Dr. Wang say “To be heard is equal to be masked”?

A

If the sound can be masked, that means that it is heard by the hair cells/SGN of the channel that is represented in the critical band. If the neuron or behavioral hearing can be masked, the masker can be heard.

47
Q

Based on the masking tuner curve, when do we know that no masking can be produced as it relates to the tone?

A

The masking tuning curve tells us that if the masker spectrum is too far away from the tone, no masking can be produced.

48
Q

How does masking relate to the critical band?

A

The CB can also be defined by masking. If the masker spectrum is too far away from the targeted tone, no masking can be produced. Therefore if broadband is used as a masker, only energy in a certain band is effective. Only the masker in the CB can be heard.

49
Q

What is the critical band proportional and used in the clinic?

A

The CB is proportional to the central frequency (20% or 1/3 octave). Therefore we use a 1/3 octave band of noise as the masker in the clinic since only the noise energy inside this band is effective.

50
Q

What are the three types of masking and signal relationships?

A

Forward, simultaneous and backward masking.

51
Q

What is the difference between monotonic and dichotic masking?

A

In monotonic, the masker and probe with the signal are in the same ear, but for dichotic, the probe with the signal is in one ear and the masker in the other. Dichotic is mainly by central masking, so weaker than monotonic which is by energetic masking.

52
Q

Where is the masking effect largest?

A

Closer to the masker onset and offset.

53
Q

What are the two ways that frequency is processed (for us to perceive it)

A

Place code and temporal code

54
Q

Describe both of Place and Temporal Coding:

A

Place coding (shown with the tuning curve of individual neurons, the behavioral tuning curve examined by masking, and the critical band as it relates to frequency discrimination). Temporal code is shown by phase locking.

54
Q

Describe both of Place and Temporal Coding:

A

Place coding (shown with the tuning curve of individual neurons, the behavioral tuning curve examined by masking, and the critical band as it relates to frequency discrimination). Temporal code is shown by phase locking.

CMSD6310 Audition l (16 decks)

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